Surgical filament assemblies

ABSTRACT

A suture anchor, and a surgical filament assembly using same, capable of being fixated in a hole formed in a bone of a patient. The suture anchor preferably includes an anchor body with a passage extending from a proximal end toward a distal end, and at least one bone engaging feature on the exterior of the anchor. A knot patency element disposed within the passage holds a removable sliding knot formed, using the surgical filament. A tightening limb of the sliding knot enables the user to tighten the sliding knot against an object extending through a capture loop to secure the object to the anchor.

RELATED APPLICATIONS

This application is a divisional application of U.S. patent application Ser. No. 13/435,790 entitled SURGICAL FILAMENT ASSEMBLIES, filed Mar. 30, 3012, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to anchors and filament assemblies for securing tissue to bone and more particularly to adjustable tensioning of tissue independent of anchor fixation.

2. Description of the Related Art

A common injury, especially among athletes, is the complete or partial detachment of tendons, ligaments or other soft tissues from bone. Tissue detachment may occur during a fall, by overexertion, or for a variety of other reasons. Surgical intervention is often needed, particularly when tissue is completely detached from its associated bone. Currently available devices for tissue attachment include screws, staples, suture anchors and tacks.

Arthroscopic knot tying is commonly practiced in shoulder rotator cuff and instability procedures. Typically, an anchor loaded with suture is attached to bone first. The suture is normally slidably attached to the anchor through an eyelet or around a post, such that a single length of suture has two free limbs. One limb of the suture is passed through soft tissue to be repaired such as a tendon or labrum. The two ends of the suture are then tied to each other, thereby capturing the soft tissue in a loop with the anchor. Upon tightening the loop, the soft tissue is approximated to the bone via the anchor.

Surgeons typically tie the suture ends by first placing a surgical sliding knot such as the Tennessee Slider or Duncan Knot. After tightening the loop, a number of additional half hitches or other knots are tied. The additional knots are needed because a conventional sliding knot does not provide the necessary protection against loosening or slippage, especially when tension is placed primarily on the limbs of the loop. Generally accepted practice is to follow the sliding knot with at least three reversed half hitches on alternating posts of the suture.

Before one or more half hitches or other knots can be added to the sliding knot, however, there exists a potential for the sliding knot to slip, that is, for the loop to enlarge as the tissue places tension on the loop. This has been referred to as “loop security” and can reportedly occur even in the hands of very experienced surgeons. Sometimes, even fully-tied knots may slip. Further, the overall size of a conventional knot can be obstructive or intrusive, especially in tight joints, which may damage cartilage or other tissue by abrasion with the knot.

Suture anchor systems with sliding and locking knots for repairing torn or damaged tissue include U.S. Pat. No. 6,767,037 by Wenstrom, Jr. Other suture anchor systems suited especially for meniscal repair are disclosed in U.S. Pat. No. 7,390,332 by Selvitelli et al. and are utilized in the OmniSpan™ meniscal repair system commercially available from DePuy Mitek Inc., 325 Paramount Drive, Raynham, Mass. 02767.

One of the present inventors is also an inventor of U.S. application Ser. No. 13/218,810 entitled “Surgical Filament Snare Assemblies”, filed 26 Aug. 2011, which claims priority to U.S. Provisional Application No. 61/416,562 filed 23 Nov. 2010 and to U.S. patent application Ser. No. 12/977,146 (Hernandez et al.) and Ser. No. 12/977,154 (Sengun et al.) filed 23 Dec. 2010.

There are a number of suture implant systems which proclaim to be “knotless”, that is, to not require a surgeon to tie a knot during surgery. Many such systems control tension on tissue by the depth to which an anchor is driven into bone. U.S. Pat. Nos. 5,782,864 and 7,381,213 by Lizardi disclose certain types of suture anchors which capture a fixed-length loop of suture. Adjustable loop knotless anchor assemblies utilizing an anchor element inserted into a sleeve are described by Thal in U.S. Pat. Nos. 5,569,306 and 6,045,574 and in U.S. Patent Application Publication No. 2009/0138042. Other allegedly knotless anchoring devices are disclosed in U.S. Pat. No. 7,682,374 by Foerster et al. and in U.S. Patent Application Publication No. 2008/0009904 by Bourque et al. Yet other systems having clamps or other locking mechanisms include U.S. Pat. No. 5,702,397 by Goble et al. and U.S. Patent Application Publication No. 2008/0091237 by Schwartz et al.

It is therefore desirable to have robust yet adjustable fixation of tissue while minimizing both the number and size of knots to be tied by a surgeon, especially during arthroscopic repair procedures.

SUMMARY OF THE INVENTION

An object of the present invention is to meet or exceed the tissue tension control and holding power of currently available suture anchor assemblies for tissue repair procedures while reducing the number of half hitches or other knots to be tied by a surgeon.

Another object of the present invention is to maintain a tied but not fully tightened knot within the suture anchor until deployment is desired.

A still further object is to simplify the overall knot tying process for the surgeon.

Yet another object of the present invention is to enable incremental tensioning of tissue after anchor fixation.

This invention features a suture anchor for use as a surgical filament assembly capable of being fixated in a hole formed in a bone of a patient. In some embodiments, the suture anchor includes an anchor body having a distal end, a proximal end, a passage extending from the proximal end toward the distal end, at least one feature disposed on the exterior of the anchor to engage bone, and a filament knot patency element disposed within the passage and defining a channel having a sufficient size, that is, minimum cross-sectional area, to allow movement of a first portion of a surgical filament therethrough when a removable sliding knot is formed, using the surgical filament, about the filament knot patency element.

In one embodiment, the filament knot patency element includes a hollow, substantially cylindrical member defining the channel as an internal passageway through the member. In another embodiment, the knot patency element is a means for maintaining patency of the sliding knot until a user manipulates at least a second portion of the surgical filament to tighten the sliding knot and slidably remove the knot from the knot patency element. Preferably, the knot patency element is formed integrally with the anchor body as a substantially tubular member that extends proximally within the passage of the anchor body. The knot patency element may define at least one feature that alters the tendency of the slip knot to reside on the knot patency element, such as one or more of an outer surface that tapers in increasing cross-sectional area proximally to encourage knot removal, an outer surface that tapers in increasing cross-sectional area distally to retard knot removal, at least one rib or other type of projection, at least one depression or other type of indentation, texturing, and coatings that alter the coefficient of friction for at least a portion of the outer surface of the knot patency element.

This invention also features a surgical filament assembly including a first filament having a sliding knot removably positioned about the knot patency element, with a shortening limb and a tightening limb each extending from the sliding knot. The sliding knot defines an adjustable capture loop having two legs extending proximally to a bight, one leg transitioning into the shortening limb and passing through the channel of the knot patency element, the shortening limb being accessible to enable a user to shorten the capture loop. The tightening limb extends proximally, over at least an initial portion of its length, to enable the user to tighten the sliding knot against an object extending through the capture loop to secure the object to the anchor.

In some embodiments, the object is a second filament capable of being passed through tissue to be repaired and then passable through the capture loop to enable incremental tensioning of the tissue after the anchor is fixated in bone, the capture loop strangulating the second filament when tension is applied to at least the tightening limb of the first filament. In other embodiments, a portion of the shortening limb is passed through tissue and then through the capture loop. In certain embodiments, a mechanism locks the shortening limb in a desired position.

A suture anchor according to the present invention in one embodiment comprises an anchor body having a distal end and a proximal end. A suture construct couples to the anchor body, the suture construct comprising a length of suture having a knot. A knot patency element on the body is removably received within the knot and holds the knot in a first non-cinched configuration. The knot also has a second cinched configuration.

Preferably, the suture construct further includes a collapsing loop formed through the knot. Preferably, the collapsing loop comprises a shortening limb passing through the knot, the shortening limb being slidable through the knot when the knot is in the uncinched configuration. When the knot is in the cinched configuration, sliding of the shortening limb through the knot is inhibited by the knot. In one aspect of the invention, a tissue suture is received through the collapsing loop. The tissue suture passes through or around a tissue to attach the tissue to the anchor. The tissue suture can comprise a fixed end of the knot.

Preferably, the knot patency element comprises a tube received within the knot and a tube cannulation through the tube. Preferably, the suture construct further comprises a collapsing loop formed through the knot and the collapsing loop comprises a shortening limb passing through the knot. The shortening limb is slidable through the tube cannulation and through the knot when the knot is in the uncinched configuration to collapse the collapsible loop. When the knot is in the cinched configuration sliding of the shortening limb through the knot is inhibited by the knot.

Preferably, the anchor body comprises a body cannulation therethrough from the proximal end to the distal end and the tube is disposed within this body cannulation. Preferably, the shortening end extends distally from the knot and exits the body cannulation at the body distal end. Preferably, the collapsing loop extends proximally out of the body cannulation at the body proximal end.

A feature can be provided to alters the tendency of the knot to stay on the patency element. For instance, the patency element can have a length and a free end which is removable from the knot and a change in circumference of the patency element along its length toward its free end could be provided to increase or decrease the tendency of the knot to slide off of the patency element.

A locking mechanism can be associated with the body for receiving the shortening limb so as to lock the shortening limb in a desired position.

This invention may be expressed as a method of surgically repairing tissue by selecting an anchor capable of being fixated in bone and having a filament knot patency element with a sliding knot in a first filament removably positioned about the knot patency element, the first filament having a shortening limb and a tightening limb each extending from the sliding knot. The sliding knot defines an adjustable capture loop having two legs extending proximally to a bight, one leg transitioning into the shortening limb and passing through the channel of the knot patency element. The shortening limb is accessible to enable a user to shorten the capture loop. At least a portion of an object is passed through a portion of the tissue and then passed through the capture loop. The anchor is fixated in bone. The tissue is then tensioned as desired and the tightening limb is manipulated so that the capture loop strangulates the object when tension is applied to at least the tightening limb to enable incremental tensioning of the tissue after the anchor is fixated.

In some embodiments, the shortening limb is manipulated to reduce the size of the capture loop as desired, preferably after the portion of the object is passed through the capture loop. In certain embodiments, the object is a second filament capable of being passed through tissue to be repaired and then passed through the capture loop to enable incremental tensioning of the tissue after the anchor is fixated in bone.

BRIEF DESCRIPTION OF THE DRAWINGS

In what follows, preferred embodiments of the invention are explained in more detail with reference to the drawings, in which:

FIG. 1 is a schematic side cross-sectional view of a suture anchor according to the present invention having a filament knot patency element;

FIG. 2 is a view of FIG. 1 with a first filament having a sliding knot removably positioned about the knot patency element to form a surgical filament assembly with capture loop according to the present invention;

FIG. 3 is a schematic perspective, partial cross-sectional view similar to FIG. 2 showing a object passed through tissue and then through the capture loop of an alternative surgical filament assembly according to the present invention;

FIG. 4 shows the surgical filament assembly of FIG. 3 after the capture loop has been shortened and the suture anchor fixated in bone, without showing the object or tissue;

FIGS. 5 and 6 are sequential views of the filament assembly of FIG. 4 as the slip knot is tightened and removed from the knot patency element;

FIGS. 7-9 are schematic views of one technique for forming the slip knot shown in FIGS. 2-6;

FIG. 10 is a view similar to FIG. 7 illustrating an alternative knot patency element; and

FIGS. 11-14 are side views of the proximal portion of yet other alternative knot patency elements;

FIG. 15 is a schematic side partial cross-sectional view of yet another suture anchor according to the present invention having an internal movable locking element;

FIG. 16 is a view similar to FIG. 15 with a first filament positioned to form another surgical filament assembly according to the present invention; and

FIG. 17 is a view similar to FIG. 16 of yet another surgical filament assembly according to the present invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

This invention may be accomplished by a suture anchor, and a surgical filament assembly using same, capable of being fixated in a hole formed in a bone of a patient. The suture anchor preferably includes an anchor body having a distal end, a proximal end, a passage extending from the proximal end toward the distal end, at least one feature disposed on the exterior of the anchor to engage bone, and a filament knot patency element disposed within the passage, that is, disposed internally within the anchor body. The filament knot patency element defines a channel having a sufficient minimum cross-sectional area to allow movement of a portion of a surgical filament therethrough when a removable sliding knot is formed, using the surgical filament, about the filament knot patency element.

The surgical filament assembly preferably includes a first filament such as a suture having a sliding knot removably positioned about the knot patency element, with a shortening limb and a tightening limb each extending from the sliding knot. The sliding knot defines an adjustable capture loop having two legs extending proximally to a bight, one leg transitioning into the shortening limb and passing through the channel of the knot patency element, the shortening limb being accessible to enable a user to shorten the capture loop. The tightening limb extends proximally, over at least an initial portion of its length, to enable the user to tighten the sliding knot against an object extending through the capture loop to secure the object to the anchor.

One construction of a suture anchor according to the present invention is shown in cross-section in FIG. 1 as suture anchor 10 having a substantially cylindrical anchor body 12 defining a central passage 14 extending from proximal end 16 toward distal end 18, which includes a sloped surface 19 to assist insertion into a hole formed in bone of a patient. In this construction, a filament knot patency element 20 is formed as an integral tube 22 within passage 14 and defines a passageway 24 as a channel extending to distal end 18. In this construction, passageway 24 may be interpreted as a distal extension of passage 14 to enable open communication between proximal end 16 and distal end 18, although open communication between ends 16 and 18 is not a limitation of the invention. The outer surface of tube 22 preferably is sufficiently smooth, that is, has a sufficiently low coefficient of friction, to enable a knot to slide along its surface as described in more detail below. A plurality of bone-engaging features 30, such as ribs or a helical thread, enhance fixation of anchor 10 after it is inserted into the hole in bone.

Anchor 10 is shown in FIG. 2 as part of surgical filament assembly 40 according to the present invention with filament 42. A removable slip knot 43 is tied about knot patency element 20 with a capture loop 44 having legs 46 and 48 extending proximally to a bight 50. Leg 48 transitions through slip knot 43 and knot patency element 20 to become shortening limb 52. The other free limb extending from slip knot 43 is a tightening limb 54.

Another construction of a suture anchor according to the present invention is shown in FIG. 3 as suture anchor 60 having anchor body 62 formed as a hollow cylinder with outer surface 63 having one or more bone engagement features. Component 70 has a base 71 with a distal surface 72 which forms distal tip 64 of anchor 60. A tubular structure 74 extends proximally from base 71 to form knot patency element 76. A slip knot 80 of first filament 82 is tied about knot patency element 76, and is removable as described in more detail below, to establish surgical filament assembly 83 according to the present invention. Component 70 is formed from the same conventional material as anchor body 62 in some constructions and, in other constructions, is formed from a different material, preferably with a low coefficient of friction especially for tubular structure 74. In some constructions, tubular structure 74 has substantially parallel walls and, in other constructions, has one or more of the shapes and features described below in relation to FIGS. 11-14.

Capture loop 84 emerges proximally from anchor 60 and is shown with a first portion 92 of an object 90 passing through capture loop 84 after passing through tissue T. Another portion 94 of object 90, on the opposite side of tissue T, is also passed through capture loop 84 in some constructions, such as where object 90 is a second filament. In another construction, shortening limb 86 serves as the object 90; in other words, portion 94 is connected to shortening limb 86 in that construction and only a single limb of first filament 82 extends through capture loop 84. In all constructions, tightening limb 88 is accessible external to the anchor, either proximally or distally, as described in more detail below. Manipulating a portion of shortening limb 86, such as by pulling it away from anchor 60, will draw object portion 92 toward anchor 60 as capture loop 84 is reduced in size.

Anchor 60 is shown in FIG. 4 inserted into a hole in bone B, preferably after capture loop 84 has been drawn toward or within anchor 60 by manipulation of shortening limb 86. To allow partial insertion of the anchor 60 into the hole while still allowing manipulation of the tensioning limb 86 the suture can exit the anchor through a side window (not shown) preferably distal of the engagement features. After the loop 84 is adjusted as desired the anchor 60 would then be fully inserted to capture the limb 86. Object 90 and tissue T have been omitted from FIG. 4 for ease of illustration. In one construction, shortening limb 86 is locked in position by frictional engagement between outer surface 63 of anchor 60 and bone B. In other constructions, shortening limb 86 is held in position by a locking mechanism or other arrangement such as described in relation to FIGS. 15 and 16 below.

Suitable instruments for inserting anchors 10 and 60 into a hole drilled in bone include cannulated drivers such as described in Cauldwell et al. in U.S. Patent Application Publication No. 2008/0147063, incorporated herein by reference. In one construction, suture anchor 10, FIGS. 1 and 2, is similar to the cannulated suture anchor disclosed by Cauldwell et al. having a post-like suture-engaging member or other occluding element over which one or more sutures or suture limbs pass to serve as a restriction to proximal movement of the first filament. Because a post-like suture-engaging member enables a limb of the first filament to reverse direction and extend proximally, open communication with a distal end of the anchor is not required.

In one procedure according to the present invention, after the anchor 60 has been inserted into bone B, FIG. 4, a surgeon or other user places desired tension on limb 92 of object 90 and grasps tightening limb 88 to withdraw tightening limb away from anchor 60 as indicated by arrow 89, FIG. 5. This action tightens slip knot 80 and moves knot 80 proximally over knot patency element 76, as illustrated in FIG. 5, and then enables capture loop 84, FIG. 6, to strangulate one or more objects previously placed through capture loop 84. When tightening limb 88 is pulled sufficiently, the capture loop 84 may draw captured objects through the knot 80 to the other, distal side of knot 80. Further tensioning tightens the knot 80. When the one or more captured objects are pulled within knot 80, a surgeon or other user may feel a “flip” or “click” signifying that knot 80 has been sufficiently tightened.

The anchor 60 could also be used as the lateral anchor in a dual row rotator cuff procedure. It would receive a suture or sutures from one or more medial row anchors (not shown) through the capture loop 84 which would then be tightened to capture the suture from the medial row anchors. One or more knots could be placed into this suture to prevent it from slipping back through the capture loop 84.

One technique for constructing filament assembly 83 is depicted in FIGS. 7-9. First filament 82 is passed through passageway 77 and a portion of tightening limb 88 is brought against the outer surface of tubular structure 74 of knot patency element 76 to form capture loop 84 and knot loop 100, FIG. 7. Tightening limb 88 is then wrapped a plurality of times, preferably two to four complete turns, around tubular structure 74, FIGS. 8 and 9, and then is passed through knot loop 100 as shown in FIG. 9. Slip knot 80 is secured in place by applying appropriate tension on tightening limb 88. In another manufacturing technique, slip knot 80 is pre-tied external to a suture anchor and then embedded in the anchor to achieve the placement and configuration shown in FIG. 9.

Alternative knot patency elements according to the present invention have one or more channels formed as slots or other features to enable a shortening limb to pass through a sliding knot removably held by a knot patency element. For example, surgical filament assembly 83 a, FIG. 10, has a tubular structure 74 a of knot patency element 76 a defining a slot 77 a to enable shortening limb 86 a of filament 82 a to slide along slot 77 a to reduce the size of capture loop 84 a after a sliding knot (not shown) is tied through knot loop 100 a but not fully tightened.

The outer geometry or surface of the knot patency elements can be modified to have one or more features that alter the tendency of a slip knot to reside on the knot patency element, such as one or more ribs or projections 110 for knot patency element 112, FIG. 11, or one or more depressions or indentations 120 for knot patency element 122, FIG. 12. The projections 110 and indentations 120 may serve as features assisting retention of a slip knot about the corresponding structure, whether tubular or other geometry, until deployment is desired. Alternatively or in addition to such discrete knot retention features, the outer surface of the knot patency element can be tapered as shown for surface 130, FIG. 13, such as frusto-conically in increasing diameter proximally if knot patency element 132 has a tubular structure, or with one or more facets increasing in width proximally if knot patency element 132 has a geometry other than cylindrical. Similarly, to enhance removal of a slip knot, a proximally-tapered surface 140, FIG. 14, can be utilized as shown for knot patency element 142. The coefficient of friction can be increased as desired, such as by texturing, or decreased as desired by providing a smooth surface. The coefficient of friction is altered in other constructions utilizing a medical-grade coating. Further, at least some of the structure of the knot patency element can be collapsible, when sufficient tension is applied to a tightening limb, to assist release of the slip knot.

An alternative multi-part suture anchor 150 according to the present invention is shown in FIG. 15 having anchor body 152, a locking mechanism 154, and a knot patency element 156. In one construction, anchor body 152 and locking mechanism 154 are similar to the VERSALOK suture anchor system commercially available from DePuy Mitek, Raynham, Mass. Anchor body 152 has alternating teeth-like projections and indentations 158 which lockably engage ribs 160 on mechanism 154 when mechanism 154 is pushed distally into anchor body 152.

Knot patency element 156 has an internal channel terminating distally in a hole 162 through which a shortening limb 161 of filament 164 is passed as shown in FIG. 16 for surgical filament assembly 166 according to the present invention. Sliding knot 168 is formed on or placed about knot patency element 156 as described above. Capture loop 170 and tightening limb 172 are directed proximally through mechanism 154. In the configuration and position shown in FIG. 16, shortening limb 161 can be manipulated to shorten capture loop 170. Once a desired size and position of capture loop 170 has been achieved, before or after an object is placed through or into capture loop 170 as desired, mechanism 154 is advanced distally to interlock with teeth 158, thereby locking shortening limb 161 into a fixed position. Final tightening of capture loop 170 to strangulate the object is accomplished by applying force to tightening limb 172.

Yet another surgical filament assembly 166 a according to the present invention is shown in FIG. 17, using reference numerals similar to FIG. 16 for corresponding features, which can enable one or both of a tightening limb 172 a and a shortening limb 161 a to extend distally beyond distal tip 178 a of anchor 150 a. As illustrated in FIG. 17, tightening limb 172 a initially extends proximally as a first segment 182 until it passes over a bridge or post 180 and then extends distally within anchor 150 a as segment 184, emerging beyond distal tip 178 a as a user-accessible tightening limb 172 a.

Such a distal-extending configuration may be useful in certain procedures such as an “outside-in” approach to femoral fixation of an anterior cruciate ligament for knee repair, with shortening limb 161 a also extending distally or, as shown in FIG. 17, passing through hole 162 a and extending proximally similar to limb 161 of FIG. 16. Another benefit of this configuration for tightening limb 172 a, if post 180 is carried by mechanism 154 a, is that tension applied to tightening limb 172 a may provide some or all of the force to lockably engage mechanism 154 with anchor body 152 a, as long as such engagement force is less than the force required to pull sliding knot 168 a away from knot patency element 156 a.

Alternative sliding knots include surgeon slidable knots with higher load capacity such as the Tennessee Slider described in the Arthroscopic Knot Tying Manual (2005) available from DePuy Mitek, as well as the slidable, lockable knot by Wenstrom, Jr. in U.S. Pat. No. 6,767,037, and other sliding knots which can be positioned about a knot patency element of a suture anchor according to the present invention.

Preferred materials for filaments 42 and 82, as well as for object 90, include various surgical sutures, typically size 0 to size 5, such as Orthocord™ suture commercially available from DePuy Mitek, and Ethibond™ suture available from Ethicon. Orthocord™ suture is approximately fifty-five to sixty-five percent PDS™ polydioxanone, which is bioabsorbable, and the remaining percent ultra high molecular weight polyethylene, while Ethibond™ suture is primarily high strength polyester. The amount and type of bioabsorbable material, if any, utilized in the first or second filament is primarily a matter of surgeon preference for the particular surgical procedure to be performed. In some constructions, the tightening limb and the shortening limb have different colors, sizes and/or textures to assist a surgeon or other user in selecting the appropriate limb to manipulate as desired.

Thus, while there have been shown, described, and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions, substitutions, and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, it is expressly intended that all combinations of those elements and/or steps that perform substantially the same function, in substantially the same way, to achieve the same results be within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated. It is also to be understood that the drawings are not necessarily drawn to scale, but that they are merely conceptual in nature. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Every issued patent, pending patent application, publication, journal article, book or any other reference cited herein is each incorporated by reference in their entirety. 

What is claimed is:
 1. A suture anchor, comprising: an anchor body having a distal end and a proximal end; a suture construct coupled to the anchor body, the suture construct comprising a length of suture having a knot and a collapsing loop formed through the knot, the collapsing loop having a shortening limb passing through the knot; and a knot patency element on the anchor body removably received within the knot, the knot patency element having a tube and a tube cannulation extending through the tube, wherein the knot patency element is configured to hold the knot in a first non-cinched configuration, the knot having a second cinched configuration, and wherein the shortening limb is slidable through the tube cannulation and through the knot when the knot is in the uncinched configuration to collapse the collapsible loop, and the suture construct and knot patency element are configured such that sliding the shortening limb through the knot is inhibited by the knot when the knot is in the cinched configuration.
 2. A suture anchor according to claim 1 and further comprising a tissue suture received through the collapsing loop, the tissue suture being receivable through a tissue whereby the tissue is attachable to the anchor via the tissue suture.
 3. A suture anchor according to claim 2 wherein the tissue suture comprises a fixed end of the knot.
 4. A suture anchor according to claim 1 wherein the anchor body comprises a body cannulation therethrough from the proximal end to the distal end and wherein the tube is disposed within the body cannulation.
 5. A suture anchor according to claim 4 wherein the shortening limb extends distally from the knot and exits the body cannulation at the body distal end.
 6. A suture anchor according to claim 5 wherein the collapsing loop extends proximally out of the body cannulation at the body proximal end.
 7. A suture anchor according to claim 1 and further comprising at least one feature that alters the tendency of the knot to stay on the patency element.
 8. A suture anchor according to claim 7 wherein the patency element has a length and a free end which is removable from the knot and wherein the feature comprises a change in circumference of the patency element along its length toward its free end.
 9. A suture anchor according to claim 1 and further comprising a locking mechanism associated with the anchor body and receiving the shortening limb so as to lock the shortening limb in a desired position.
 10. A suture anchor, comprising: an anchor body having a distal end, a proximal end, and a longitudinal axis extending from the distal end to the proximal end; a knot patency element on the anchor body, the knot patent element comprising a tube and a tube cannulation through the tube; and a suture construct coupled to the anchor body, the suture construct comprising a length of suture wrapped transversely with respect to the longitudinal axis of the anchor body around the knot patency element a plurality of times such that the suture construct circumscribes the knot patency element transversely with respect to the longitudinal axis of the anchor body, wherein the knot patency element is configured to hold a knot of the suture construct in a first non-cinched configuration, the knot having a second cinched configuration, and the tube being received within the knot, and wherein the suture construct comprises a collapsing loop formed through the knot and the collapsing loop comprises a shortening limb passing through the knot, the shortening limb being slidable through the tube cannulation and through the knot when the knot is in the non-cinched configuration to collapse the collapsible loop, and when the knot is in the cinched configuration, sliding of the shortening limb through the knot is inhibited by the knot.
 11. A suture anchor according to claim 10 wherein the suture construct further comprises a collapsing loop formed through the knot.
 12. A suture anchor according to claim 11 wherein the collapsing loop comprises a shortening limb passing through the knot, the shortening limb being slidable through the knot when the knot is in the non-cinched configuration, and when the knot is in the cinched configuration, sliding of the shortening limb through the knot is inhibited by the knot.
 13. A suture anchor according to claim 11 and further comprising a tissue suture received through the collapsing loop, the tissue suture being receivable through a tissue whereby the tissue is attachable to the anchor via the tissue suture.
 14. A suture anchor according to claim 10 wherein the anchor body comprises a body cannulation therethrough from the proximal end to the distal end and wherein the tube is disposed within the body cannulation. 